ブラウザでのiCalの保存について
Date
Jul 6, 2020
Reactで作っているフロントエンドで、カレンダー保存機能を作っているんですが、ブラウザ側でiCalファイルをダウンロードするのが難しくないですか?

よくわからん😡 → わかった🥳

 
React Communityを覗くと、nwcell/ics.jsというパッケージが紹介されているんですが、npmがないという......。
 
どうやらインラインスクリプトを書けばできるっぽいんですが。
 
<button id="download_calendar_btn">
  Download Calendar
</button>
<script>
	var saveAs=saveAs||function(e){"use strict";if(typeof e==="undefined"||typeof navigator!=="undefined"&&/MSIE [1-9]\./.test(navigator.userAgent)){return}var t=e.document,n=function(){return e.URL||e.webkitURL||e},r=t.createElementNS("http://www.w3.org/1999/xhtml","a"),o="download"in r,a=function(e){var t=new MouseEvent("click");e.dispatchEvent(t)},i=/constructor/i.test(e.HTMLElement)||e.safari,f=/CriOS\/[\d]+/.test(navigator.userAgent),u=function(t){(e.setImmediate||e.setTimeout)(function(){throw t},0)},s="application/octet-stream",d=1e3*40,c=function(e){var t=function(){if(typeof e==="string"){n().revokeObjectURL(e)}else{e.remove()}};setTimeout(t,d)},l=function(e,t,n){t=[].concat(t);var r=t.length;while(r--){var o=e["on"+t[r]];if(typeof o==="function"){try{o.call(e,n||e)}catch(a){u(a)}}}},p=function(e){if(/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(e.type)){return new Blob([String.fromCharCode(65279),e],{type:e.type})}return e},v=function(t,u,d){if(!d){t=p(t)}var v=this,w=t.type,m=w===s,y,h=function(){l(v,"writestart progress write writeend".split(" "))},S=function(){if((f||m&&i)&&e.FileReader){var r=new FileReader;r.onloadend=function(){var t=f?r.result:r.result.replace(/^data:[^;]*;/,"data:attachment/file;");var n=e.open(t,"_blank");if(!n)e.location.href=t;t=undefined;v.readyState=v.DONE;h()};r.readAsDataURL(t);v.readyState=v.INIT;return}if(!y){y=n().createObjectURL(t)}if(m){e.location.href=y}else{var o=e.open(y,"_blank");if(!o){e.location.href=y}}v.readyState=v.DONE;h();c(y)};v.readyState=v.INIT;if(o){y=n().createObjectURL(t);setTimeout(function(){r.href=y;r.download=u;a(r);h();c(y);v.readyState=v.DONE});return}S()},w=v.prototype,m=function(e,t,n){return new v(e,t||e.name||"download",n)};if(typeof navigator!=="undefined"&&navigator.msSaveOrOpenBlob){return function(e,t,n){t=t||e.name||"download";if(!n){e=p(e)}return navigator.msSaveOrOpenBlob(e,t)}}w.abort=function(){};w.readyState=w.INIT=0;w.WRITING=1;w.DONE=2;w.error=w.onwritestart=w.onprogress=w.onwrite=w.onabort=w.onerror=w.onwriteend=null;return m}(typeof self!=="undefined"&&self||typeof window!=="undefined"&&window||this.content);if(typeof module!=="undefined"&&module.exports){module.exports.saveAs=saveAs}else if(typeof define!=="undefined"&&define!==null&&define.amd!==null){define("FileSaver.js",function(){return saveAs})}	
	/*! ics.js Wed Sept 14 2017 */
	window.ics=function(e,t){"use strict";{if(!(navigator.userAgent.indexOf("MSIE")>-1&&-1==navigator.userAgent.indexOf("MSIE 10"))){void 0===e&&(e="default"),void 0===t&&(t="Calendar");var r=-1!==navigator.appVersion.indexOf("Win")?"\r\n":"\n",n=[],i=["BEGIN:VCALENDAR","PRODID:"+t,"VERSION:2.0"].join(r),o=r+"END:VCALENDAR",a=["SU","MO","TU","WE","TH","FR","SA"];return{events:function(){return n},calendar:function(){return i+r+n.join(r)+o},addEvent:function(t,i,o,l,u,s){if(void 0===t||void 0===i||void 0===o||void 0===l||void 0===u)return!1;if(s&&!s.rrule){if("YEARLY"!==s.freq&&"MONTHLY"!==s.freq&&"WEEKLY"!==s.freq&&"DAILY"!==s.freq)throw"Recurrence rrule frequency must be provided and be one of the following: 'YEARLY', 'MONTHLY', 'WEEKLY', or 'DAILY'";if(s.until&&isNaN(Date.parse(s.until)))throw"Recurrence rrule 'until' must be a valid date string";if(s.interval&&isNaN(parseInt(s.interval)))throw"Recurrence rrule 'interval' must be an integer";if(s.count&&isNaN(parseInt(s.count)))throw"Recurrence rrule 'count' must be an integer";if(void 0!==s.byday){if("[object Array]"!==Object.prototype.toString.call(s.byday))throw"Recurrence rrule 'byday' must be an array";if(s.byday.length>7)throw"Recurrence rrule 'byday' array must not be longer than the 7 days in a week";s.byday=s.byday.filter(function(e,t){return s.byday.indexOf(e)==t});for(var c in s.byday)if(a.indexOf(s.byday[c])<0)throw"Recurrence rrule 'byday' values must include only the following: 'SU', 'MO', 'TU', 'WE', 'TH', 'FR', 'SA'"}}var g=new Date(l),d=new Date(u),f=new Date,S=("0000"+g.getFullYear().toString()).slice(-4),E=("00"+(g.getMonth()+1).toString()).slice(-2),v=("00"+g.getDate().toString()).slice(-2),y=("00"+g.getHours().toString()).slice(-2),A=("00"+g.getMinutes().toString()).slice(-2),T=("00"+g.getSeconds().toString()).slice(-2),b=("0000"+d.getFullYear().toString()).slice(-4),D=("00"+(d.getMonth()+1).toString()).slice(-2),N=("00"+d.getDate().toString()).slice(-2),h=("00"+d.getHours().toString()).slice(-2),I=("00"+d.getMinutes().toString()).slice(-2),R=("00"+d.getMinutes().toString()).slice(-2),M=("0000"+f.getFullYear().toString()).slice(-4),w=("00"+(f.getMonth()+1).toString()).slice(-2),L=("00"+f.getDate().toString()).slice(-2),O=("00"+f.getHours().toString()).slice(-2),p=("00"+f.getMinutes().toString()).slice(-2),Y=("00"+f.getMinutes().toString()).slice(-2),U="",V="";y+A+T+h+I+R!=0&&(U="T"+y+A+T,V="T"+h+I+R);var B,C=S+E+v+U,j=b+D+N+V,m=M+w+L+("T"+O+p+Y);if(s)if(s.rrule)B=s.rrule;else{if(B="rrule:FREQ="+s.freq,s.until){var x=new Date(Date.parse(s.until)).toISOString();B+=";UNTIL="+x.substring(0,x.length-13).replace(/[-]/g,"")+"000000Z"}s.interval&&(B+=";INTERVAL="+s.interval),s.count&&(B+=";COUNT="+s.count),s.byday&&s.byday.length>0&&(B+=";BYDAY="+s.byday.join(","))}(new Date).toISOString();var H=["BEGIN:VEVENT","UID:"+n.length+"@"+e,"CLASS:PUBLIC","DESCRIPTION:"+i,"DTSTAMP;VALUE=DATE-TIME:"+m,"DTSTART;VALUE=DATE-TIME:"+C,"DTEND;VALUE=DATE-TIME:"+j,"LOCATION:"+o,"SUMMARY;LANGUAGE=en-us:"+t,"TRANSP:TRANSPARENT","END:VEVENT"];return B&&H.splice(4,0,B),H=H.join(r),n.push(H),H},download:function(e,t){if(n.length<1)return!1;t=void 0!==t?t:".ics",e=void 0!==e?e:"calendar";var a,l=i+r+n.join(r)+o;if(-1===navigator.userAgent.indexOf("MSIE 10"))a=new Blob([l]);else{var u=new BlobBuilder;u.append(l),a=u.getBlob("text/x-vCalendar;charset="+document.characterSet)}return saveAs(a,e+t),l},build:function(){return!(n.length<1)&&i+r+n.join(r)+o}}}console.log("Unsupported Browser")}};
</script>
 
const newEvent = {
    BEGIN: 'VCALENDAR',
    PRODID: 'www.website.com',
    UID: 'info@website.com',
    CATEGORIES: 'APPOINTMENT',
    DTSTART: '20140321T153010Z',
    DTEND: '',
    SUMMARY: 'My great event',
    DESCRIPTION: 'Great event in your town',
    END: 'VCALENDAR',
}
 
let formattedDate = formatDate(newEvent.DTSTART)

cal = ics()
cal.addEvent(newEvent.SUMMARY, newEvent.DESCRIPTION, newEvent.PRODID, formattedDate, formattedDate)

function formatDate(dateString) {
  return dateString.replace(/(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})/,"$1-$2-$3T$4:$5:$6")
}
  
download_calendar_btn.onclick = function() {
  cal.download("my_calendar")
}
 
...なんかいい方法はないものか🧐
もう少し試行錯誤してみることにします。
 
もろもろ試行錯誤&調査を進めた結果、なんとかブラウザでiCalファイルのダウンロードに成功しました🎉(このgistがとても参考になりました。ありがとう!)
 
ファイル生成のダウンロードのリンクしているだけなんですが...
わかることとできることは全然違うことはいつでも思い知らされますね。
 
最終的には、こんな感じになりました。
export default function CalenderButton() {
  return (
    <button onClick={() => saveiCal(eventName, new Date(eventDate))}>
      iCalに保存
    </button>
	);
}

function saveiCal(eventName: string, eventDate: Date) {
  // name of event in iCal
  const eventName = `${eventName}`;

  // time of event in iCal
  const now = new Date();
  const formattedDate = toISO(eventDate);
  const dateStart = formattedDate;
  const dateEnd = formattedDate;

  //helper functions
  var icsLines = [
    'BEGIN:VCALENDAR',
    'VERSION:2.0',
    'PRODID:-//hoge//foo//JA',
    'METHOD:REQUEST',
    'BEGIN:VEVENT',
    `UID:event-${toISO(now)}`,
    `DTSTAMP:${toISO(now)}`,
    `DTSTART:${dateStart}`,
    `DTEND:${dateEnd}`,
    `SUMMARY:${eventName}`,
    `LAST-MODIFIED:${toISO(now)}`,
    'SEQUENCE:0',
    'END:VEVENT',
    'END:VCALENDAR',
  ];

  try {
    const downloadUrl = `data:text/calendar;base64,${btoa(
			// eventName等に日本語を入れるための処理 refs: https://qiita.com/lacolaco/items/89e8fc50b2d311a3b6c0
      unescape(encodeURIComponent(icsLines.join('\r\n')))
    )}`;
    saveFile(downloadUrl, eventName);
  } catch (e) {
    alert('カレンダーの登録に失敗しました。');
  }
}

const saveFile = function (fileURL, eventName) {
  //name of file to download as
  const fileName = eventName;

  const save = document.createElement('a');
  save.href = fileURL;
  save.target = '_blank';
  save.download = fileName;

  const event = new MouseEvent('click', {
    view: window,
    bubbles: true,
    cancelable: false,
  });
  save.dispatchEvent(event);

  (window.URL || window.webkitURL).revokeObjectURL(save.href);
};


function toISO(date: Date) {
  return date.toISOString().replace(/-|:|\.\d\d\d/g, '');
}
 

ちなみに。

googleカレンダーへの追加は簡単にできました。
 
ちょっとわかりづらいのはISOに準拠した日付設定時のフォーマットくらい。
(new Date()).toISOString().replace(/-|:|\.\d\d\d/g,"");
※これはiCalでも同様でした。
 

参考資料

iCalについて

ISOのフォーマットについて